Long Wave Pass Edge Filters

Often referred to as long wave pass (LWP) and short wave pass (SWP) filters, these sharp-cut edge filters are distinguished by their high rate of transition between their region of reflection and transmission. This high rate of transition makes them an excellent choice as emission filters in fluorescence applications, and as order sorting filters in photometry. They are also very useful as stray light or trim filters, to eliminate any unwanted near band radiation. All Andover LWP/SWP filters are constructed of hard, durable first-surface dielectric coatings, and will withstand the normal cleaning and handling associated with any high-quality optical component. Their film construction is essentially a modified quarter-wave stack, using interference effects rather than absorption to isolate their spectral bands. Unlike filter glass, which is not sensitive to wavelength shift with angle, these filters will shift shorter in wavelength with an increase in their angle of incidence. This feature can be useful in applications where it may be desirable to fine tune the 50% cut-on, or cut-off wavelength. All standard edge filters are available in 50nm increments from 400nm to 1000nm. Custom edge filters are available and will be quoted upon request. Please contact one of our technical sales representatives for more specific information.